Question 884702
Let {{{ s }}} = the speed of the car in mi/hr
{{{ s + 143 }}} = the speed of the plane in mi/hr
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Let {{{ t }}} = time in hrs for both
Equation for car:
(1) {{{ 50 = s*t }}}
Equation for plane:
(2) {{{ 180 = ( s+143 )*t }}}
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(2) {{{ 180 = s*t + 143t }}}
and
(1) {{{ s = 50/t }}}
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Substitute (1) into (2)
(2) {{{ 180 = (50/t)*t + 143t }}}
(2) {{{ 180 = 50 + 143t }}}
(2) {{{ 143t = 130 }}}
(2) {{{ t = .909 }}}
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(1) {{{ s = 50/t }}}
(1) {{{ s = 50/.909 }}}
(1) {{{ s = 55 }}}
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The speed of the car is 55 mi/hr
check:
(2) {{{ 180 = ( s+143 )*t }}}
(2) {{{ 180 = ( 55 + 143 )*.909 }}}
(2) {{{ 180 = 198*.909 }}}
(2) {{{ 180 = 180 }}}
OK